1. Field of the Invention
This invention relates to improvements in a wide angle lens having an angle of view of 60.degree.-70.degree. and an F-number of the order of 2.8.
2. Description of the Prior Art
In order to shorten the total length of a lens (the distance from the foremost surface of the lens to the focal plane thereof), it is known to adopt a so-called telephoto type optical system comprising a convergent forward group and a divergent rearward group. A wide angle lens using this technique is disclosed in Japanese Laid-open Patent Application No. 76147/1979 (corresponding U.S. Pat. No. 4,204,747), and this is surely shorter in total length than former wide angle lenses and succeeds in shortening the total length to the same degree as the focal length. On the other hand, however, it is a wide angle lens having a large angle of view and, therefore, the aperture of the lenses in the rearward group, particularly the lens most adjacent to the image side, is very large. Such a wide angle lens cannot be said to be compact, and it has other disadvantages. That is, if the aperture of the rearward lens is large, a large space will be required in a camera body to which such lens is mounted, and this is disadvantageous in making the camera compact. Further, the marginal light beam may be forced to possibly promote the disadvantage of a wide angle lens in which the quantity of marginal light is originally small.